Augmented reality (AR) is a term for a live direct or an indirect view of a physical, real-world environment whose elements are augmented by computer-generated sensory input, such as sound or graphics. It is related to a more general concept called mediated reality, in which a view of reality is modified by a computer. As a result, the technology functions by enhancing one's current perception of reality. By contrast, virtual reality replaces the real-world with a simulated one.
Augmentation is conventionally in real-time and in semantic context with environmental elements, such as sports scores on TV during a match. With the help of advanced AR technology (e.g. adding computer vision and object recognition) the information about the surrounding real world of the user becomes interactive and digitally manipulable. Artificial information about the environment and its objects can be overlaid on the real world.
Research explores the application of computer-generated imagery in live-video streams as a way to enhance the perception of the real world. AR technology includes head-mounted displays and virtual retinal displays for visualization purposes, and construction of controlled environments containing sensors and actuators.
As an example, AR technology can be incorporated into cell phones running on the ANDROID operating system as well as other operating systems such as iOS, PlayStation and VITA. AR has been incorporated into modem video games. AR has the ability to produce computer generated images in a user's real-world field of vision in real time.
The AR field is divided into two major areas from an algorithmic standpoint:                marker-based        positional-based        object/feature recognition        
Marker-based augmented reality is based on the computer processing of artificial markers or tags in the real world (examples: QR codes, barcodes, or similar markers) and superimpose computer-generated images based on where the markers are located. Positional-based augmented reality is based on where you are located, where you are pointing to (as in heading), and where are the objects of interest are located relative to you. The computer then will superimpose images on top of the real-world image. Some applications are hybrids of these techniques.
Marker tags are small black and white printable shapes that interact with software downloaded to a computer equipped with a webcam or a smart phone with camera to create 3-D images overlaid on the real-world image seen on screen. The markers define spatial positioning and rotation of an object or character. Refer to FIG. 1 and FIG. 2 for an example of a marker and the AR image it produces.
Object/feature recognition and positional based processing is processing that is intensive and highly inaccurate. A marker based system allows secure identification of a person (as an example) with one active marker. Optical near range recognition will be possible even in dark or smoky environments such as a bar.
One problem associated with marker tags is that they must be visible and easily recognized for the camera to recognize and interpret. Another problem associated with visible marker tags is that the camera viewing the marker must be connected to an image processor powerful enough to interpret the marker and produce the AR layover. Current cell phone technology or portable data processing technology are currently powerful enough to operate image processing technologies such as cameras but lack sufficient power to project sophisticated AR images used in modern video games using AR applications such as role playing games in which players adopt the persona and visual appearance of a game character.